Telephone line repeater



Patented July 13, 1937 PATENT OFFICE TELEPHONE LINE REPEATER Josef Kuchley, Berlin-Siemensstadt, and Walter Kusche, Berlin-Steglitz, Germany, assignors to Siemens & Halske Aktiengesellschaft, Siemensstadt, near Berlin, Germany Application December 28, 1935, Serial No. 56,430

- In Germany January 19, 1935 3 Claims.

Thepresent invention relates to a circuit arrangement for the inductive repetition of direct impulses over subscribers lines in telephone systems.

Various arrangements of this sort are already known but they possess the disadvantage that special sources of current and special transformers have to be provided at the subscribers stations. The range of the impulses is also limited. Finally, in the case of badly insulated subscribers lines in which considerable leakage occurs between the two leads and from the individual leads to earth, as is frequently the case with rural exchanges, the known arrangements do not 5 allow of impulse sending. These disadvantages are obviated according to the invention in that they impulses transmitted over the two leads of the line are inductively transmitted to the impulse receiving. relay at the incoming end of the line by means of a further repeating coil connected symmetrically between the two halves of the primary winding of the speech repeating coil.

Thearrangement according to the invention has the particular advantage that it allows an undistorted transmission of impulses even when there is considerable leakage between the leads of the line and between the leads and earth, because the impulse relay does not respond to interruptions in the current but to current variations.

The attached drawing represents three embodiments of the invention. Fig. 1 is a diagrammatic circuit drawing of one form of the invention, while Figs. 2 and 3 are similar circuit draw ings showing two desirable modifications. Fig. 1 represents a subscribers automatic telephone station N which is connected with an exchange over the subscriber's line TL. If a connection with another subscriber is to be set up from the subscribers station N the receiver is first removed and relay S is accordingly energized over the. contact HU of the switchhook. Relay S closes both its contacts is and 2s and thereby connects earth to the two leads of the subscriber's line TL by way of the impulse con- .tact mi and windings I and II of the choke coil B. Two parallel circuits are thus set up from earth over the two leads TL of the subscribers line, windings al and a3, and a2 and (L4 to battery. The windings al and 112 are the two halves of the primary winding of the speech repeating coil Trl, which transmits the speaking currents to the secondary windings bl and b2. Windings a3 and at are the two halves of the primary 55 winding of an impulse repeating coil T12 over which the impulses are transmitted inductively to the secondary windings b3 and b4 and the polarized impulse receiving relay J in series therewith. The primary windings al and a2 of the speech repeating coil Trl are connected up so 5 that they are both arranged in the same direction relative to the speaking currents traversing the speaking leads in series and consequently transmit the speaking currents to the secondary windings bl and b2 by induction. The'two wind- 10 ings al a2 of the repeater Trl, as regards the setting impulses traversing the two leads of the line in parallel, are connected in opposite senses relative to one another. The magnetic fields produced in this repeating coil by impulses accord- 15 ingly neutralize one another so that the windings do not present any inductive resistance to the passage of the impulses. On the other hand the primary windings a3 and at of the impulse repeater TrZ which are connected in series with the windings al and a2 are arranged in such a manner that they are traversedin opposite senses by the speaking currents so that they do not present any inductive resistance to these currents, while they are traversed by the setting impulses 25 transmitted over the leads in parallel in the same sense, so that the impulses are inductively transmitted to the secondary windings b3 and b4 and thus to the polarized receiving relay J.

The closing of the two parallel impulse cir- 30 cuits on removing the receiver at the subscriber's station causes the operation of the armature of the polarized relay J at the exchange which may, for example, be used for seizing the line.

On displacing the dial during dialing windings 35 I and II of the choke coil B are short-circuited by the contact nsa. When the dial returns to normal this short-circuit is removed. During the motion of the dial the impulse contact nsi is alternatively opened and closed in the known man- 40 ner. When the parallel circuits are broken the impulse receiving relay J in the exchange returns its armature to normal and when these circuits are closed the armature is again attracted. Relay J transmits the setting impulses to an operating magnet which is not shown. The releasing occurs when the receiver is replaced at the subscriber's station N. Relay S thereupon deenergizes and by opening its contacts Is and 2s breaks the parallel circuits. In the exchange relay J returns its armature permanently to the rest position and thereby causes the release or the connecting device in the exchange.

Fig. 2 represents a further embodiment of the invention. In this case, however, the impulse repeating coil Tr2 does not possess two primary windings, as in Fig. 1 but only a single primary winding :13 which is connected to the point; of symmetry between the two primary windings al and c2 of the speech repeating coil Trl. The impulses are transmitted by induction from the primary winding a3 as to secondary winding b3 and thence to the polarized impulse receiving relay J. Otherwise the switching proceedings are similar to those of Fig. 1. v I

Fig. 3 shows an arrangement in which in contra-distinction to those of Figs. 1 and2 which are adapted for local battery feeding, the feeding of the subscriber takes place from batteryat the exchange. tional impulse repeating coil 'Ir2 is connected to a point arranged symmetrically between the two primary windings of the speech repeating coil Trl. The other end of the winding is connected to battery. The two primary windings of the speech repeating coil are connected in the known manner througha condenser. Earth is, connected betweenthis condenser and the lower winding of the transformer. The impulses are transmitted to the impulse repeating coil Tr2 by means of the subscribersdial through interruptions inthe loop over the 'subscribers line and the subscribers station. These are transmitted by the repeater Tr2 to the polarized receiving relay J.

What is claimed is:

1. In a telephone line, means for transmitting impulses over the two sides of said line in parallel, a speech repeating coil havingthe outside ends of the primary windings connected to said line, an impulse repeating coil having its primary windings connected between the inside ends of the The primary winding (13 of the addi-- ed to the secondary winding of said impulse repeating coil, the impulses received over said line being inductively repeated by the windings of the impulse repeating coil to the impulse relay.

2. In a telephone system, a line extending from.

a station to an exchange, means for transmitting speech currents over the two sides of said line in series, means for transmitting setting impulses over the two sides of said line in parallel, a repeating coil at the exchange having its primary. windings connected to said line cumulatively as regards speech currents and differentially as regards setting impulses, whereby only speech currentsare repeated by said repeating coil, a second repeating coil at the exchange having its primary windings connected to said line diiferentially as regards speech currents and cumulatively as regards impulses, whereby only impulses are repeated by said second repeating coil, and an impulse responding relay connected in circuit with the secondary windings of said second repeating coil.

3. In a telephone system, aline extending from a station to an exchange, said line including a repeating coil at the exchange for repeating speech currents, a simplex dialing circuit superimposed on said'line, said circuit including the two sides of said line in parallel," two primary windings of said repeating coil inparallel, and a current source at the exchange, a second repeating coil at the exchange having its primary wind ings included in said simplex circuit, and. an impulse responding relay in circuit with the secondary windings of said second repeating coil, the said first and second repeating coils being so connected to the line as to be selectively responsive to speech currents transmitted over the two sides of theline in series and impulses transmitted over said simplex circuit, respectively. J OSEF KUCHLEV.

WALTER KUSCHE. 

